Under the provisions of the Consumer Rights Act 2015, you have the 'right to reject' goods that aren't 'of satisfactory quality' and/or aren't 'as described'.
Section 20(8) of the Act specifically states: "Whether or not the consumer has a duty to return the rejected goods, the trader must bear any reasonable costs of returning them, other than any costs incurred by the consumer in returning the goods in person to the place where the consumer took physical possession of them".